Silicas Chemically Modified with Sulfur-Containing Groups for Separation and Preconcentration of Precious Metals Followed by Spectrometric Determination

Silicas chemically modified with a number of sulfur-containing groups (mercaptopropyl, mercaptophenyl, dipropyl disulfide, thiadiazole thiol, dithiocarbamate and thiourea derivatives) were proposed for the separation and preconcentration of precious metals. These adsorbents quantitatively extracted precious metals from 0.5 to 4 M solutions of hydrochloric acid. It allowed their separation from high concentrations of non-ferrous, alkaline earth, alkali and some other related metals. The selectivity of separation of kinetically labile precious metal ions in ligand substitution reactions from kinetically inert ones depended on the nature of sulfur atom within the functional group of adsorbents and increased when passing from thione to thiol sulfur. Approaches for the preconcentration of precious metals using silicas chemically modified with sulfur-containing groups prior to their AAS, ICP-OES, and ICP-MS determination in ores, concentrates and their processing products were proposed. The correctness of the developed methods was confirmed by the analysis of certified reference materials.

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Preconcentration And Determination Of Precious Metals Using Silica Gel Chemically Modified With Products Of Interaction Of O- or p-Aminotiophenols With g-(Trietoxisilane)Propylisocyanate

METHODS AND OBJECTS OF CHEMICAL ANALYSIS ◽

10.17721/moca.2020.53-65 ◽

2020 ◽

Vol 15 (2) ◽

pp. 53-56

Author(s):

A.K. Trofimchuk ◽

V.N. Losev ◽

V.V. V.V. ◽

E.V. Elsuf’ev ◽

N.V. Gudymа

Keyword(s):

Precious Metals ◽

Silica Gels ◽

Luminescence Spectroscopy ◽

Surface Complexes ◽

Chemically Modified ◽

Gold Silver ◽

Lower Oxidation ◽

Sulfur Containing ◽

Better Than

The synthesis of new complexing adsorbents with thiophenol (MPhS) and aminobenzthiazolpropyl (ABTS) groups grafted onto the surface of silica gels are considered. The extraction of precious metals (Au(III), Ag(I), Pd(II), Pt(II,IV), Rh(III), Ir(IV), Ru(IV), Os(IV)) from solutions of hydrochloric acid by MPhS and ABTS adsorbents. Contact time, acidity, temperature (25 – 95 °C), and the presence of a labilization agent tin(II) chloride is examined. It is shown that the adsorption properties of MPhS for precious metals are better than ABTS. It was proved by luminescence spectroscopy that gold, silver and platinum in the surface complexes with sulfur-containing groups are in lower oxidation states; and by the EPR method it was proved that ruthenium and osmium in surface complexes are in oxidation state +3. The formation of luminescent Ag(I), Au(I) and Pt(II) complexes on the surface of the MPhS, colored Ru(III) complexes on the surface of MPhS and ABTS, and mixed-ligand complexes of Pt(II) with surface aminobenzthiazole groups and Michler’s thioketone were used for developing methods of their adsorption luminescent, adsorption-photometric and test determinatio

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Separation and preconcentration followed by ICP-OES and ICP-MS determination of precious metals using silica gel chemically modified with dithiocarbamate groups

Separation Science and Technology ◽

10.1080/01496395.2019.1655454 ◽

2019 ◽

Vol 55 (15) ◽

pp. 2659-2669 ◽

Cited By ~ 1

Author(s):

Vladimir N. Losev ◽

Victoriya V. Parfenova ◽

Evgeney V. Elsuf’ev ◽

Elena V. Borodina ◽

Segey I. Metelitsa ◽

...

Keyword(s):

Silica Gel ◽

Precious Metals ◽

Icp Oes ◽

Chemically Modified ◽

Icp Ms ◽

Separation And Preconcentration

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Green Dispersive Micro Solid-Phase Extraction using Multiwalled Carbon Nanotubes for Preconcentration and Determination of Cadmium and Lead in Food, Water, and Tobacco Samples

Current Analytical Chemistry ◽

10.2174/1573411014666180619145236 ◽

2020 ◽

Vol 16 (4) ◽

pp. 381-392

Author(s):

Ayman A. Gouda ◽

Ali H. Amin ◽

Ibrahim S. Ali ◽

Zakia Al Malah

Keyword(s):

Carbon Nanotubes ◽

Solid Phase Extraction ◽

Multiwalled Carbon Nanotubes ◽

Solid Phase ◽

Certified Reference Materials ◽

Phase Extraction ◽

Multiwalled Carbon ◽

Flame Atomic Absorption ◽

Relative Standard ◽

Separation And Preconcentration

Background: Cadmium (Cd2+) and lead (Pb2+) have acute and chronic effects on humans and other living organisms. In the present work, new, green and accurate dispersive micro solid-phase extraction (DμSPE) method for the separation and preconcentration of trace amounts of cadmium (Cd2+) and lead (Pb2+) ions in various food, water and tobacco samples collected from Saudi Arabia prior to its Flame Atomic Absorption Spectrometric (FAAS) determinations was developed. Methods: The proposed method was based on a combination of oxidized multiwalled carbon nanotubes (O-MWCNTs) with a new chelating agent 5-benzyl-4-[4-methoxybenzylideneamino)-4H- 1,2,4-triazole-3-thiol (BMBATT) to enrich and separate trace levels of Cd2+ and Pb2+. The effect of separation parameters was investigated. The validation of the proposed preconcentration procedure was performed using certified reference materials. Results: Analyte recovery values ranged from 95-102%, indicating that the method is highly accurate. Furthermore, precision was demonstrated by the relative standard deviation (RSD < 3.0%). The limits of detection were 0.08 and 0.1 μg L−1 for Cd2+ and Pb2+ ions, respectively. The preconcentration factor was 200. Conclusion: The proposed method was used for the estimation of Cd2+ and Pb2+ ion content in various real samples, and satisfactory results were obtained. The proposed method has high adsorption capacity, rapid adsorption equilibrium, extremely low LODs, high preconcentration factors and shortens the time of sample preparation in comparison to classical SPE.

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Gold recovery from flotation concentrate from gold mine tailings using dissolve smelting

Journal of Mining and Metallurgy Section B Metallurgy ◽

10.2298/jmmb181005038e ◽

2019 ◽

Vol 55 (3) ◽

pp. 343-349

Author(s):

U. Erdenebold ◽

C.-M. Sung ◽

J.-P. Wang

Keyword(s):

Molten Slag ◽

Precious Metals ◽

Copper Slag ◽

Molten Copper ◽

Flotation Concentrate ◽

Sulphide Minerals ◽

Oxidative Roasting ◽

Valuable Metals ◽

Gold Mine Tailings ◽

High Concentrations

Gold flotation concentrate may contain relatively high concentrations of valuable metals such as iron, copper, and zinc, and occasionally, even precious metals such as gold. The major components of the concentrate are SiO2, Fe2O3, and Al2O3, but it also contains reactive sulphide minerals such as pyrite. The sulphides in the flotation concentrate are fully converted into an oxide form during oxidative roasting, therefore, the chemical composition of the roasted concentrate is considered to be a copper slag. High temperature smelting with additives to dissolve Au from the gold concentrate into a molten copper was used in the research. Gold greatly dissolved at 1600?? under a CaO/SiO2 ratio of 1.25, suggesting the increase in the dissolution of gold into molten copper with decreasing viscosity of the molten slag-like concentrate at high temperatures.

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Rapid capture of trace precious metals by amyloid-like protein membrane with high adsorption capacity and selectivity

Journal of Materials Chemistry A ◽

10.1039/c9ta12124b ◽

2020 ◽

Vol 8 (6) ◽

pp. 3438-3449 ◽

Cited By ~ 7

Author(s):

Facui Yang ◽

Zhigang Yan ◽

Jian Zhao ◽

Shuting Miao ◽

Dong Wang ◽

...

Keyword(s):

Metal Ions ◽

Adsorption Capacity ◽

Precious Metal ◽

Precious Metals ◽

Bilayer Membrane ◽

High Adsorption ◽

Protein Membrane ◽

High Adsorption Capacity ◽

Precious Metal Ions

A protein-based bilayer membrane can selectively sequester precious metal ions from leaching solutions of ores and WEEE, and exhibits an adsorption capacity for gold of 1034.4 mg g−1.

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Design and synthesis of thiourea derivatives with sulfur-containing heterocyclic scaffolds as potential tyrosinase inhibitors

Bioorganic & Medicinal Chemistry ◽

10.1016/j.bmc.2016.03.013 ◽

2016 ◽

Vol 24 (8) ◽

pp. 1866-1871 ◽

Cited By ~ 9

Author(s):

Pingping Liu ◽

Chen Shu ◽

Lujie Liu ◽

Qingchun Huang ◽

Yanqing Peng

Keyword(s):

Thiourea Derivatives ◽

Design And Synthesis ◽

Tyrosinase Inhibitors ◽

Sulfur Containing

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Biosorption of Precious Metal Ions by Magnetically Activated Sludge Cultured Bacteria

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.152-154.46 ◽

2012 ◽

Vol 152-154 ◽

pp. 46-51

Author(s):

Fang Cai ◽

Jin Sheng Sun ◽

Ting Ting Zhao ◽

Jing Li

Keyword(s):

Activated Sludge ◽

Metal Ions ◽

Precious Metal ◽

High Selectivity ◽

Anaerobic Bacteria ◽

Precious Metals ◽

Aerobic Bacteria ◽

Adsorption Effect ◽

Precious Metal Ions ◽

Cultured Bacteria

Although biosorption for reclaiming single precious metal was frequently reported, the actual subsistent adsorptive competition among different metal ions sometimes shows diverging reinforcement or prohibition for different species. This study tries to screen bacteria that are able to absorb certain precious metals with high selectivity under competitive conditions. The activated sludge was cultivated from enrichment by magnetotactic bacteria medium proposed by Blakemore. Then four microbes, microaerobic bacteria(A) acclimated micro-aerobic bacteria (B), anaerobic bacteria(C) and acclimated anaerobic bacteria(D) were obtained for the following adsorption experiments. The four microbes have high removal efficiency of Au3+ both in its unitary and Au3+-Cu2+binary system. The microaerobic bacteria (B) are good metal catchers and carriers for the uptake of gold in aquatic solution with coexistence of copper. In Pd2+-Cu2+system, there is a collaborative adsorption effect, especially on (B).

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Viscosity and voluminosity of caseins chemically modified by reductive alkylation with reducing sugars

Journal of Dairy Research ◽

10.1017/s0022029900033318 ◽

1988 ◽

Vol 55 (4) ◽

pp. 539-546 ◽

Cited By ~ 15

Author(s):

Bernard Colas ◽

Christine Gobin ◽

Denis Lorient

Keyword(s):

Steric Hindrance ◽

Structural Changes ◽

Reducing Sugars ◽

Negative Charge ◽

Covalent Binding ◽

Rheological Parameters ◽

Flow Properties ◽

Chemical Modifications ◽

Chemically Modified ◽

High Concentrations

SummaryThe effect of the covalent binding of reducing sugars such as galactose, glucose, fructose, lactose and maltose on the flow properties of casein solutions and on the voluminosity of casein molecules was investigated, voluminosity being calculated from viscosity measurements. Rheological parameters appeared to be efficient indices of structural changes occurring in proteins as a result of chemical modifications. Results showed an increase in voluminosity of casein after the binding of sugars, possibly explained by an increase in the net negative charge or by an increase in the steric hindrance of the molecule. At high concentrations (above 0·03 g/ml), viscosity of the solutions depended on the nature of the attached sugar and on the level of the modification. Thus galactose- and glucose-modified caseins were more viscous than the control. With disaccharides, the level of modification appeared to be more important than the amount of sugar bound.

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